Effect Of Anhydrous Gypsum Of FBC On The Properties Of Concrete And Interfacial Transition Zone

The technology of CFB(circulating fluidized bed)coal desulfurization is a kind of advanced coal combustion technology.However,the characteristics of the FBC(circulating fluidized bed combustion ash)can not be known,and there is no comprehensive utilization of economic and mature ways,which results in the limited promotion of the technology.FBC is essentially a burnt clay mineral,using it in the building materials widely is an effective way.However,the FBC contains large amounts of anhydrous gypsum,whose solubility is closely related with temperature.And the humidity has a great influence on the formation of AFt.In this paper,we take anhydrous gypsum in FBC insteading of dihydrate gypsum into the cement production.It also explores the influence of the cement concrete on the concrete properties and the interfacial transition zone(ITZ)under different curing conditions.The different curing temperature before hardening was 20 ?,60 ? and 90 ?.Curing Humidity is set to the four different ways after stripping,such as water maintenance,standard maintenance,seal maintenance and nature maintenance.This article is helpful to understand the anhydrous gypsum in FBC correctly,and it also makes great contributions to dealing with the FBC properly.In order to obtain the rules which the anhydrous gypsum affects on the concrete.The mechanical properties,durability and ITZ of the two types of concrete are compared,which one concrete is mixed by the cement of anhydrous gypsum in FBC,the other one is mixed by dihydrate gypsum.(1)Research results show that the curing temperature largely affects the 3 d compressive strength of the first concrete(concrete is mixed by the cement of anhydrous gypsum FBC)comparing with the second concrete(concrete is mixed by the cement of dihydrate gypsum).(2)Curing humidity affects the 28 d compressive strength of two kinds of concrete seriously.The highest compressive strength is 27.5 MPa,which is in water curing condition and 20 ? before stripping.Comparing with the second concrete,its compressive strength increased by 40% in the same curing condition.For the curing humidity,the highest compressive strength is about 60 MPa in the water curing condition.The lowest compressive strength is about 42 MPa.(3)For the durability of concrete,two kinds of concrete are significantly affected by the curing humidity and their influence on the two kinds of concrete is the same.The durability of concrete in the water curing condition is the best.The durability of concrete in the nature curing conditions is the worst.(4)For the ITZ of concrete,the maximum microhardness of ITZ is in the water curing condition,and the width of ITZ is about 60 ?m.The minimum microhardness is in the nature curing condition,and the width of its ITZ is about 80 ?m ~ 100 ?m.In a word,the influence of curing temperature and curing humidity on the two kinds of ITZ is basically the same.In a word,ensuring the total SO3 content in concrete,the cement mixed by the anhydrous gypsum in FBC can be safely applied into the concrete under the condition of suitable dosage.